A. Field of the Invention
This invention relates to apparatus for covering submerged conduit, and more particularly to a submersible apparatus adapted to cover the conduit with material gathered from the sea bottom.
B. Background of the Prior Art
An offshore conduit resting on the sea bottom can be exposed to various hazards, including hydrodynamic forces, fishing trawls, and dragging anchors. Currently, offshore conduits are disposed in trenches cut into the sea bottom by various apparatus, thereby lowering the pipeline below the level of the surrounding sea bottom. However, existing equipment used to dig trenches for submerged conduits do not include positive means for refilling such trenches. In most cases, the trench remains open unless it becomes filled due to the natural motion of the water near the sea bottom. As long as the conduit is not covered, it remains exposed to the majority of hazards that exist along its length.
Various arrangements have been suggested to cover submerged conduits. One such arrangement includes a plow or blade that is towed adjacent to the length of the conduit by a surface vessel. The blade scrapes and moves laterally sea bottom material over the conduit. However, the blade arrangement has a number of disadvantages, including requiring excessive vessel power for towing and threatening to damage the conduit. Another method has included depositing over the conduit material gathered onshore. This method is not satisfactory because of the capacity necessary to bring the material to the conduit location.